1. Field of the Invention
This invention relates generally to alarm systems and more particularly to a self-contained monitor surveilling a predetermined space in a premises for an occurrence of an alarm condition. The self-contained monitor communicates with a telephone answering machine such that the occurrence of the alarm condition is recorded on the answering machine and may be subsequently retrieved therefrom by an authorized user.
2. Description of Related Art
Alarm systems which may be accessed and tested by an authorized user are well known in the art. In certain systems, the authorized user calls a telephone number associated with the system and is connected directly thereto in order to prompt either a response regarding its status or to reprogram selected system functions.
Self-contained monitors that surveil a predetermined space in a premises for a specific alarm condition are also known in the prior art. One such device, a Passive Infrared (PIR) monitor surveils the predetermined space for an intruder. This type of monitor is either armed and disarmed by a coded input to a keypad which is an integral part of the monitor or is armed, disarmed and tested by a remote controller which transmits a Radio Frequency(RF) signal that is activated by an authorized user. When employing a system having a remote controller, a returning occupant is able to stand outside his or her premises and, before entering, test the monitor to determine if an intruder remains therein in order to avoid a dangerous confrontation. When employing a monitor which utilizes a keypad, the returning occupant cannot test the monitor from outside the predetermined space and therefore enters the premises to disarm the monitor using the keypad thereby risking the possibility of encountering a remaining intruder.
Further, there are self-contained alarm monitors available in the industry which may be positioned in a premises to monitor for an alarm condition other than a break-in, for example, smoke or freezing temperatures. Generally, such monitors are used in a system which includes an automatic dialer that is programmed to dial the telephone number of a phone located outside the premises in order to alert a person answering the phone that an alarm condition exists at the premises.
U.S. Pat. No. 4,085,292 which issued to David L. Leslar, and John C. Kirk on Apr. 18, 1978 discloses an improved combination alarm and automatic telephone answering system for connection to a telephone line which is adapted to permit a person to determine the existence of one or more alarm conditions at a remote location by telephoning a predetermined telephone number at the remote location and listening for a coded signal indicative of normal or alarm conditions. In an optional mode, the incoming call is not answered to thereby signify normal conditions. The telephone answering system taught by Leslar does not comprise a standard telephone answering machine. Leslar""s answering system includes a line grabbing circuit which enables a sequence interrogator to select one or more alarm sensors in succession so that if an alarm condition is detected, a long single tone is fed into the telephone system. Leslar does not teach an alarm monitor that transmits an alarm message to a user""s standard telephone answering machine to be recorded thereon. In addition, Leslar does not disclose a system wherein the authorized user can either dial the telephone number of his or her answering machine from a distant telephone in order to remotely retrieve the alarm message or enter his or her premises and manually activate a speaker which is normally an integral part of a standard telephone answering machine in order to locally retrieve the alarm message therefrom. Finally, Leslar does not disclose a self-contained monitor which communicates with an answering machine via RF signals.
U.S. Pat. No. 5,402,466 which issued to Thomas C. Delahanty on Mar. 28, 1995 teaches an automatic paging system that will alert a paging service subscriber to the occurrence of specific events at a remote location. The paging system works in conjunction with a user""s existing paging subscription services and answering machine which is employed to record incoming calls originating from a caller using a distant phone. The system detects if either a valid message has been left on the answering machine by the caller or if an alarm has been tripped. Should either event occur, the system dials a number that the user programs into the system that corresponds to the paging service number, waits for an acknowledgement tone from the paging service, and then dials a distinct code that corresponds to what has occurred at the remote location. The system will forward a telephone number to the paging service subscriber, if such a number has been entered into the answering machine by the caller. When an alarm is tripped, the phone line is seized and the system dials the preprogrammed pager number, waits for the acknowledgement tone, and then transmits a numerical code depending on which alarm has been triggered. Delahanty does not teach a self contained monitor which, when tripped, causes an alarm message to be transmitted to the user""s answering machine which may be queried either remotely by the user calling from a distant telephone or locally by the user manually activating a speaker which is part of the telephone answering machine in order to listen to the alarm message recorded thereon. The answering machine disclosed by Delahanty is employed to record routine incoming messages from callers attempting to reach the occupant of the premises in which his system is located. Delahanty""s answering machine does not communicate with a self-contained alarm monitor in order to record the occurrence of an alarm condition on the answering machine which may be queried by an authorized user of the system.
U.S. Pat. No. 5,808,547, a continuation-in-part of U.S. Pat. No. 5,621,385, which issued to the applicant of the present invention, William P. Carney, on Sep. 15, 1998 discloses an intrusion detection system used to surveil a predetermined space in a premises for an occurrence of an intrusion wherein a self-contained monitor may be armed, disarmed and tested by a remote controller transmitting an RF signal initiated by a user manipulating a button switch. In addition, the disclosure teaches that the transmitting device operates in a manner similar to a garage door opener. However, the disclosure does not teach a self-contained monitor which communicates the occurrence of the intrusion via RF signaling to the occupant""s standard telephone answering machine located in the premises so that the occupant can interrogate the answering machine to check for the intrusion.
As can be seen from the foregoing, there is a need in the industry for a cost effective alarm system in which a self-contained monitor communicates the occurrence of an alarm condition to a standard telephone answering machine located in a premises, thus enabling an occupant to interrogate the answering machine for the occurrence of the alarm condition. Further, there is a need for a means by which to easily adapt the standard telephone answering machine to enable it to communicate, via RF signaling, with the self-contained monitor so that both the answering machine and the monitor may be positioned at optimum locations within the premises without concern for any wiring required to interconnect them. Finally, there is a need for such a system in both apartment buildings and houses wherein it is convenient and cost effective for an occupant to utilize his or her existing telephone answering machine as part of the system and inconvenient and costly to install the wiring and special telephone equipment normally required for prior art systems.
The present invention is directed to an alarm system that solves the problem of providing a simple and cost effective means by which a self-contained monitor communicates the occurrence of an alarm condition in a predetermined space to a standard telephone answering machine associated therewith, thus enabling the user to interrogate the answering machine for telephone messages left thereon by callers and for the occurrence of the alarm condition.
The present invention comprises a self-contained monitor which defines a sensor armed for sensing the alarm condition and a monitor transmitter coupled to the sensor which transmits a monitor signal in response thereto. An interface module communicates with a telephone line and a telephone answering machine associated with the predetermined space. The interface module includes an interface receiver circuit which receives and processes the monitor signal, a message generator which provides an alarm message, an off-hook telephone circuit which has a message input and a message output, a line simulator which has a simulator input and a simulator output which provides a telephonic connection therethrough and which applies a ringing voltage to the simulator output, and a transfer switch which has a normal position and an activated position. The message generator is coupled to the message input, the message output is coupled to the simulator input, the transfer switch is coupled to the simulator output and the interface receiver circuit. Further, the telephone answering machine is coupled to the telephone line in the normal position, is disconnected therefrom and coupled to the simulator output in the activated position, also, the message generator, the off-hook telephone circuit and the line simulator are activated therein. Responding to the monitor signal, the interface receiver circuit operates the transfer switch to the activated position wherein the off-hook telephone circuit prompts the line simulator to apply the ringing voltage which causes the telephone answering machine to pick up thereby completing the telephonic connection through which the alarm message is transmitted from the message generator to the telephone answering machine.
In addition, the interface receiver circuit further comprises a timing circuit which holds the transfer switch in the activated position for a time period at least long enough for the alarm message to be recorded on the answering machine before prompting the transfer switch to return to the normal position. Subsequently, the user calls the telephone line to access the answering machine in order to retrieve the alarm message.